Unlike the $1.9 trillion Covid-19 stimulus act, the next initiative, which is expected to be even bigger, won’t rely just on government debt as a funding source. While it’s been increasingly clear that tax hikes will be a component — Treasury Secretary Janet Yellen has said at least part of the next bill will have to be paid for, and pointed to higher rates — key advisers are now making preparations for a package of measures that could include an increase in both the corporate tax rate and the individual rate for high earners.